This study will identify a large cohort of patients at Mass General Hospital and Children's Hospital in Boston with Cystic Fibrosis Arthropathy (CFA) for a comprehensive case-controlled investigation of the prevalence, clinical characteristics, genotype analysis, and health status of patients with CFA. Although the existence of arthropathy associated with CF has been suggested, relatively little is known regarding its prevalance, clinical characteristics and course. The combined CF population at Children's and the MGH provide the opportunity to study arthropathy in CF.